Who ya gonna call?
by ZoeTheineffable
Summary: When parapsychologist professors Sam, Dean and Cas get fired from their jobs at the university of Columbia, they decide to use their newfound knowledge of the existence of ghosts to start a successful business of Ghost busting. But when Gabriel starts being haunted by a demon in his fridge will they be able to save the world? Sastiel, Debriel based on ghostbusters movie
1. If there's something strange

**Disclaimer: I own neither supernatural or Ghostbusters**

**So I was watching Ghostbusters and I thought "Wouldn't a Supernatural Ghostbusters AU be freaking amazing!" so this was written.**

* * *

**Chapter 1**

Dean really had to say, he loved his job. Being one of the professors of parapsychology at Columbia University was _awesome_. He got to work with his two favourite people in the world, Sam his younger brother and his best friend Castiel, and all he had to do was a study or two a year.

Like right now. It was a study on how the use of negative reinforcement of a mild electrical shock could increase the levels of ESP in some people. Or at least it had been, until one of his participants had exercised his Right to Withdraw by withdrawing from the room.

At least he still had one participant, Lisa Braeden a literature student who had absolutely no psychic abilities whatsoever, not that Dean had told her that.

"Do you really think I could be psychic, Dr Winchester?" she asked looking up with wide eyes full of wonder at the professor across from her.

"Well, Ms Braeden, I gotta say, no one has ever guessed that many cards correctly in the five years I have been working at this university. I think you have a real natural talent." He lied, watching as her smile managed to grow impossibly wider. "In fact, I think with some nurturing this talent of yours, it could be something brilliant."

Lisa opened her mouth to say something but was interrupted by the door banging open and Sammy running in yelling "Dean!"

Dean's protective older brother instincts flared up and he stood "Sammy? What's wrong?"

"Dean, you got to come with me to the Central Library right now!" Sammy had long brown hair that curled down past his ears and he towered over his brother and everybody else in the world. He was wearing a familiar plaid shirt and old blue jeans.

"Excuse me a moment," he said to Lisa and pulled Sam into a remote corner with him and said "Sammy, I'm kinda in the middle of something here!" gesturing towards Lisa.

"I'm sorry, Dean, but we found an actual ghost!" He said, his face lit with an excited smile. "This afternoon ten people at the New York Public Library saw a Free Floating Full Torso Vaporous Apparition throwing books off shelves and scared a librarian half to death!"

"Well, that's great Sammy!" Dean crowed slapping his brother's shoulder affectionately "You and Cas need to go down there, get some data and come show me, okay?" He started to walk back over to Lisa when Sam grabbed his arm stopping him in his tracks.

"No, Dean, you gotta come with us, Cas is already down there taking EMF readings and their off the charts! This is the big one Dean! We're going to make history!" He nailed Dean with his large soulful puppy dog eyes that had never failed at making Dean give Sam whatever he wanted.

"Alright." Dean grumbled "But this better not turn out to be some whacked out Schizophrenic who's off their meds again."

"Dean, that was one time!" Sam protested.

"Yeah, yeah. Sorry about this Ms Braeden, we're gonna have to take a rain check but how about we meet up for dinner tonight, say about…"

"Eight?"

"That is exactly what I was about to say!" He heartily ignored the way Sammy rolled his eyes beside them as he ushered Lisa out of the room before them and they started to walk out of building.

"Seriously, Dean? She's a student!" He complained shaking his head in disgust as they climbed into Dean's car, a 1967 Impala that was previously owned by their dad.

"Not my student." He pointed out as he started the car and slid a Led Zeppelin CD into the player.

"So not the point Dean." He murmured but couldn't comment further as Dean turned the music up to an eardrum damaging level a clear sign that the conversation was over.

* * *

Sam and Dean jogged up the libraries steps and hurried inside. They found Cas knelt down by a table near the entrance, a stethoscope plugged into his ears and pressed to a table.

"What the hell is your boyfriend doing?" Dean asked watching Cas shift the listening piece across the table with a look of intense concentration on his face.

"Shut up, Dean, he's not my boyfriend." Sam protested blushing slightly and tapping Cas's shoulder to get his attention. Dean just grinned, Sammy had been pretty much been in love with Cas since he'd met the guy at college, years before. Dean had never been able to work out how they had never gotten together.

"Hello Dean, Sam." Cas said standing up straight. Cas was almost the polar opposite of the two brothers. He was shorter than them both and also had a much less muscled frame. He also had a wide spread of stubble across his lower jaw while the two boys preferred to be clean shaven and fluffy brown hair that was often messy. A fawn coloured trench coat hung over his wiry frame and gave him the overall appearance of a tax accountant. "Sam, why are you blushing?"

"I, er, how about we go talk to the librarian now?" He deflected and quickly walked towards an office. Dean hid a grin and sauntered after him with Cas who was looking confused as usual.

Dean really couldn't work out how Cas had not realised that Sam was head over heels in love with him yet, considering that it had been going on pretty much since they'd met each other but then Cas was socially inept and tended to be confused by social cues that most people understood instinctively.

They finally caught up with Sam as he entered a small office where the librarian, a pretty young woman with black hair, was lying on a wooden desk with a coat pillowed under her head. Sam was still looking a little shifty around Cas and Dean rolled his eyes subtly. As much as he enjoyed teasing his brother about Cas it was honestly getting annoying to watch him pine over the guy all the time. He was pretty tempted to just give Cas a shake and point out the obvious but he knew that Sam wouldn't appreciate him messing about in his love life.

Besides, he had no idea how Cas felt about Sam and he didn't want to potentially ruin what the three of them had going by pointing it out so he was saying silent for now.

The librarian was introduced to them as Ava Wilson and Dean started to question her while Sam and Cas discussed some of the readings they'd gained quietly near the door.

"Miss Wilson, I'd just like to ask you some questions about what you saw this afternoon, could you tell me what happened?"

"I was returning some books that had been taken out to the shelves in the basement when I heard this noise like many pieces of paper being thrown into the air. I turned around and the reference cards were flying out the drawers on their own! There wasn't any kind of breeze to explain so I panicked and run away and I ran round a corner and I saw it!"

"It?"

"A Free Floating Full Torso Vaporous Apparition." Cas broke in.

"Er, yeah, what he said." Ava agreed slightly confused.

"Miss Wilson, have you or any member of your family been diagnosed with schizophrenia?"

"Are you saying I'm crazy?" She sat up and glared at Dean who put on his best placating smile and said "No, Miss Wilson, I'm just covering all bases, so have you?"

"No, not officially, but my uncle thought he was Saint Jerome."

Dean blinked in surprise and said "I think that qualifies. Do you regularly partake in substances with hallucinogenic properties?"

"I'm not a drug addict either!" She protested.

"Of course not. Just standard questions, Miss Wilson." He soothed. He was about to ask another when Cas squinted down at the piece of equipment in his hand and interrupted.

"Sam, Dean, its moving. Follow me." He quickly walked out of office with Sam on his heels. Dean sighed and picked up his jacket. It was going to be a long afternoon.

* * *

He followed Cas and Sam through a rabbit warren of book shelves taking turns at random, it seemed to Dean. He really hoped this didn't turn out to be a wild goose chase or he would be seriously pissed off. It didn't take him long to get bored and he started whistling 'The Twilight Zone' theme tune until Sam turned around and punched his arm.

"Ow! What the fuck!" He cursed and glared at Sam's bitchface.

"Quit fooling around Dean! This is serious." He hissed.

"Sam we've been walking around here for ten minutes and no sign of any ghosts!" Dean complained "It's probably just another wild goose chase."

"Sam, Dean come here." Cas called from a few aisles away. The two brothers turned a corner and saw Cas standing next to a neat stack of books in the centre of the aisle. Cas was scanning the book stack with the strange device he'd been using to track the supposed ghosts movement and looked at them, his ocean blue eyes were lit with excitement and said "Here is your sign, Dean."

"Oh yeah," he scoffed "because a human would never stack books like this."

"It's just like the Philadelphia mass disturbances in 1947! Symmetrical book stacking." Sam breathed out in awe and looked up and down the pile. Dean rolled his eyes.

"Hey, do you guys smell that?" Sam asked, sniffing the air like a bloodhound and slipping past the book stack without knocking it down. Following his nose, Sam lead them around a corner and they found the corridor which held the reference cards. Some of the drawers had been pulled out as far as they could go and the cards from them littered the floor. They were also covered in a thick gooey substance that looked a lot like something had sneezed over drawers.

"Ectoplasmic residue." Cas identified it as and pulled an empty petri dish from his trench coat and demanded "Dean, collect a sample."

"Oh no! I'm not touching that crap! Not a chance in hell."

"Dean, collect a sample!" Cas growled glaring at the other man. Cas might have been a small guy but he could still be damn intimidating when he wanted to.

"Fine," Dean relented "But you so owe me pie." He snatched the dish from Cas's outstretched hand and scraped the goo off of a nearby draw. Sam and Cas continued on the trail wondering further between the shelves leaving Dean to it.

"Aw man, this is damn skivvy." He complained as part of it oozed onto his hand when he shut the lid.

As soon as he caught up with Sam and Cas he wiped his hand on Sam back without him noticing and said "Here's your damn snot, Cas. What do you want it for anyway?"

"I wish to analyse it later." He murmured slipping it back into his coat and then saying "Be quite, we are close."

They continued stalking through the book shelves and eventually the handheld device, of which the explanation had almost caused DEan to fall asleep standing up, started to make an obnoxiously high pitched beeping sound.

They turned a corner and gasped collectively.

"Son of a bitch." Dean murmured "It's an actual ghost!"


	2. In your neighbourhood

**Disclaimer: I don't own Supernatural or Ghostbusters**

**Chapter 2**

* * *

The ghost was about three metres further down the aisle, hovering a few feet off the ground. It looked like it had been a lady while it was alive, as it had long hair that was piled up onto its head in a severe bun hairstyle and was wearing an old fashioned dress that faded out, along with the rest of its body, into a white mist swirling above the ground. It was holding a book in its hands and was idly turning the pages slowing like it was flicking through the book for the hell of it.

"I knew it!" Sam muttered, fumbling in a satchel Dean had only just noticed, and pulled out a handheld video camera and switched it on. He then turned to Dean and grinned "I told you ghosts were real, Dean, and here's the proof!"

Dean was grinning along with his brother, he was glad that Sam and Cas had been proved right, it had always been his brother's dream to prove that ghosts were real ever since he'd seen their Mom's ghost back when he was a kid. However now they had found a ghost, it raised an important question.

"Well, what do we do now?" Dean asked looking over at the other two scientists for clarification.

Sam and Cas froze, looked at each other and then looked at Dean.

"Okay, can I talk to you two over here please?" He grabbed Sam's arm and dragged him back down the aisle hoping Cas would follow. "Okay, Samantha, are you telling me you two have been dragging me about New York City for the past two years looking for these damn ghosts and you haven't even worked what to do after you've found one?"

"We have never thought that far ahead." Cas said in his normal gravelly voice. Sam looked at the ground sheepishly and Cas glared at the machine in his hands as if it had an answer.

"You seriously have no idea do you? Oh God." He swiped his hand across his face. "Okay you got any suggestions, Einstein's?"

"Well, we gotta make contact with it, right? One of us has got to go talk to it, see why it hasn't moved on or something?" Sam suggested.

"Good idea, Sam." Cas praised and Sam blushed and practically preened. Dean rolled his eyes, geez the guy was transparent. He realised soon though, that they were both looking at him.

"Oh no, I already gathered that weird ass goo for you two, there's no way in hell that I'm talking to that ghost." Dean refused.

"Come on, Dean!" Sam wheedled, the puppy dog eyes appearing.

"No way, Sam! It's _your_ damn life's work, you go talk to it!"

"Dean," Cas said, his voice slipping into a commanding growl, "I cannot talk to it because, as you are fond of pointing out, I have poor people skills and Sam cannot talk to it as he will be recording the encounter from a safe distance, in case the ghost wishes to attack."

"Oh fine," he grumbled "But I am so getting pie out of this." and practically stomped back down to where the ghost was still reading with Sam and Cas following.

"Er, hello, Miss? My name's Dr Dean Winchester, that's my brother Sam and our friend Cas. Er, where are you from?" he asked.

The ghost turned its head away from the book and stared at Dean for a few seconds before it lifted its finger to its lips and shushed him.

His eyes widened in shock and he looked back at Sam and Dean and said "Any more bright ideas?"

Sam ran a hand through his hair and said "Okay, I got an idea, follow me."

He strode past Dean towards the ghost but before he could get very close a strange thing occurred. The ghost suddenly turned towards them and seemed to expand to twice its size and screamed. The noise was incredibly loud and blood-curdling, the sort of noise Dean imagined somebody being murdered might make. The lights around them flickered as the ghost continued to grow and Dean could see that his brother was panicking in front of him, his large geek brain short-circuiting in fright.

"Come on, Sam!" Dean yelled over the noise, reaching over and grabbing a handful of his brother's plaid shirt, tugging him into action and running alongside him as they followed Cas out of the library basement, past the library patrons and into the open air.

* * *

"Oh my God, I can't believe that just happened! We just got chased out of library by a damn ghost." Dean laughed as they walked through a nearby park.

"I know, I can't believe it either! After so many years, we finally have proof! We touched the Etheric Plane!" Sam's face was filled with boyish glee and he had a bounce in his step that had been missing for many months.

"Yeah, yeah it'll be bigger than the microchip." Dean joked, though a similar wide grin was splitting his own face. Sam's excitement had always been contagious to Dean and adding the fact that a boat load of adrenaline was still in his system it was no surprise he was feeling so damn pleased.

Cas was trailing behind the two brothers, still squinting at the results he'd gained on the hand held device. Dean knew he'd catch up with them when he was ready so he let Cas squint and continued celebrating with Sam over their success until Cas suddenly interrupted. He caught up with the two brothers and stood at Sam's side while he announced "Using the readings I've gained, we should be able to design a way to contain an Ectoplasmic entity indefinitely."

"Are you serious?" Dean asked as Sam looked over Cas's shoulder at the results.

Cas blinked at him in surprise and said "I'm always serious."

"It's an expression, Cas." Dean said, shaking his head slightly at how clueless Cas could be some times. "He right, Sam?" He asked his brother.

"Well, sure. I mean, it would assume that the ionization rate for all Ectoplasmic Entities is a constant but, it's possible theoretically." Sam said looking at Dean briefly before turning back to the results.

"Well, come on, let's go talk science back at the University, huh?" Dean said clapping his brother on the shoulder and leading them both to where the Impala was parked.

* * *

Sam and Cas were still talking about how they would be able to build the ghost containment facility when they arrived back at their office and found that their equipment was being removed by workmen. Overseeing the procedure was Michael, the Dean of the university.

"Dean Michael, what is going on here?" Cas asked, as an important piece of equipment was taken out of room.

"Are we being moved to a new office?" Sam asked, already looking like he suspected the answer was no but asking anyway.

"No, Doctor Winchester, you are being moved out of this room and this university. The board has decided to cut funding to all of your projects, effective immediately." He said it with glee, he'd had it out for the three of them since they'd arrived.

"What?" Dean yelled "You can't just chuck us out without any notice like that!"

"Oh yes I can, Dr Winchester because, you see, at this university we believe that the purpose of science is to serve mankind whereas you, however, seem to consider it some kind of a hustle, used to keep you from any proper work. Your theories are the worst kind of popular tripe, your conclusions are highly questionable, and in short you are a poor scientist. In fact, all three of you are!"

Dean clenched his fists and glared at Michael, seriously considering punching him but Sam grabbed his arm and said "Dean, no, he's not worth it. Let's just go."

* * *

"What the hell do we do now?" Sam asked, his head in his hands.

After some discussion, the three men had travelled to a nearby diner they had often frequented over the years to make a new plan. Sam and Dean were sat on one side of the booth and Cas had sat on the other side and was looking as miserable as Sam.

"I mean," Sam continued "No University is going to employ us after this! Forget Stanford and Hardvard now, we might as well have been blacklisted."

"Don't you worry Sammy." Dean grinned "I got a plan." Sam raised his head and stared at him in confusion along with Cas. "But first, you owe me pie for collecting your ghost snot. Oh and for talking to it"" He said to Cas.

"Your obsession with pie is getting worrying." Cas grumbled, but he still flagged down the waitress and ordered Dean a slice.

"So what's your plan?" Sam asked as Dean was handed a plate of apple pie and Cas put his wallet away.

"How about you, me and Cas go into business together?" He gestured at each person in turn with his laden fork before putting it in his mouth and moaning. He was going to miss this pie.

"Business? Doing what?" Sam asked incredulously.

"Catching ghosts, obviously." The looks of confusion had come back to their faces. "Think about it, there's gotta be plenty of ghost's that people want to get rid of, enough that they would pay someone to get rid of them."

"You want to start a ghost extermination business?" Cas asked, his brow furrowed.

"Why not? We're the only ones around so we'll guaranteed business."

"Dean," Cas said, "We don't have enough funds to start a business."

"Yeah, Cas is right Dean." Sam added "Where would we find the cash? The bank isn't exactly going to just give us a loan."

Dean hesitated and said slowly "We've still got Dad's life insurance money left."

Sam made a face "Dean, no, we promised we'd use it for something worthwhile, that would make him proud and anyway I don't even think there is enough money for what you have in mind."

"What would make him prouder than us going into business together? Come on, wouldn't it be great to be working together, just the three of us? No freaking Michael's on our back's all the time, being our own bosses?"

"Well, yeah," Sam admitted, "But Dean how would we afford it?"

"We'll come up with something." He said confidently, and forking the last section of pie into his mouth. "We always do."

* * *

The 'something' turned out to be borrowing money from Bobby, one of their Dad's old friends. Two days after being fired, the three of them took the long trip by car from New York to Sioux Falls where Bobby lived.

Bobby had taken Sam and Dean in after their Dad had died, when Dean was six and Sam had been four. He'd been a good father to them, despite his gruffness and they felt kind of bad asking him for any amount of money after all he'd done for them.

"You want to do what?" Bobby asked staring at the three men. They shifted in their seats nervously as he regarded them rather like they had back when they had been kids and had done something wrong.

"We want to start a ghost exterminating business." Sam repeated, feeling nervous and babbled "Look, Bobby me and Cas we've worked it all out and we're pretty sure we'll be able to capture ghosts and hold them indefinitely, if that's what you're worried about."

"And you know we'll pay you back every cent." Dean added, looking at his adopted father earnestly.

He ran a hand over his face. "That's not what I'm concerned about. I know you'll pay me back and I trust your ability, Sam and Cas. What I _am_ concerned about is how you're going to turn all this into a business. God, I'm probably going to regret this but I'll give you the money."

"Thanks Bobby, you won't regret it, I promise."

"Yeah, yeah. You boys are going to be the death of me. All these grey hairs I got? You caused every single one." He grumbled.

* * *

It took another few days of searching before they found a suitable base of operations to set up their business. The estate agent, a tall woman with brown hair in a severe bun named Naomi showed them around an old fire department that had been closed down due to government cuts.

"As you can see, the building needs a lot of work before it can be lived in, but it has a very affordable price." Naomi explained.

Dean stared at the debris and cobwebs on the ground floor. Sam had run off to look upstairs leaving him and Cas alone with Naomi.

"What do you think Cas?" He asked.

"I think this building should be condemned. There is serious metal fatigue in all the load baring members making collapse likely. The electrical wiring is substandard and even if it is was perfect, the building would still be completely inadequate for our powering needs. I think we should look elsewhere."

"Don't hold back, Cas." Dean muttered, sarcastically and earned himself a glare. He was about to tell the lady they wouldn't take it when they heard Sam yell from above them "Hey, does this pole still work?" and turning, they saw Sam slide down the one remaining firemen's pole. He practically bounced over to them excitedly and gushed "Wow, guys, this place is amazing! We've got to get it! There are plenty of rooms upstairs for building equipment and sleeping and things!" He turned to Naomi and asked "When can we move in?" before running out to the car.

Dean and Cas stared at each other, while Naomi smirked at them. Cas seemed to be waging an inner war against his common sense, knowing the building was terrible and Sam's obvious happiness. After a minute of internal debate, Cas visibly slumped and said "We'll take it." mournfully.


End file.
